Harley-Davidson's Ironhead Sportster is arguably the loudest and meanest-sounding V-twin ever. Produced from 1957 to 1985, sales increased nearly every year, along with improvements in power, handling, and reliability.
The multi-cylinder motorcycle years started in 1968, with the three-cylinder Triumph Trident , followed quickly by Honda's CB750-4 in 1969. Benelli's 750 Sei was the world's first production six-cylinder motorcycle.
Offering the allure of litre-bike performance in a mid-size package, all of Japan's Big Four offered turbocharged bikes in the Eighties. As more power was coaxed out of naturally-aspirated engines, the more expensive and complex turbos fell out of favor, with 1985 being the last year a production turbocharged motorcycle was offered for sale in the U.S. The quickest and most notorious of these bikes was the Kawasaki GPz-750 Turbo.